how about fire clay?

[bimfi]

I have been wanting to build a brick oven for quite a long time, but keep feeling overwhelmed about the whole aspect of purchasing and cutting and joining, etc. I have seen prefabbed dome ovens for sale, but those seem to always be way too expensive. Now, I have heard of forming a domed oven out of clay and thought that that may be a suitable substitute process. Has anyone tried this approach, and if so, what type of fire clay should I be looking for?
I read about EPK Kaolin dry clay in 50 lb bags. If this is a good type of clay, I could use it for the dome and use fire brick for the flooring. I'm thinking that a good 3" thick clay dome would be a good start, then wrap around it with and insulating blanket and then the vermiculite material for further insulation. If anyone has any suggestions, I would really appreciate it.